1. Field of the Invention
This invention relates to a submersible raft for the cultivation of plant life.
2. Description of the Prior Art
For many decades, much attention has been paid to the dangers and disastrous consequences of cutting down foliage from the countryside. Such widespread denudation of the land has resulted in erosion of precious topsoil with not only loss of valuable vegetation but also an imbalance in the insect and mammal life that were dependent upon such vegetation for continued existence.
Although the evils of soil erosion are well understood and documented, a parallel situation has existed with regard to the destruction of marine vegetation. Such destruction of aquatic plants has resulted from dredging activities, coastal developments, heated water effluents and oil pollution. The term aquatic plants includes seagrasses which are flowering submerged plants and algae which are non-flowering plants otherwise known as angiosperms. The consequences of such destruction of sea grasses, although not as readily apparent as the effects of the destruction of land vegetation, have been documented by various authors. For example, J. L. Taylor and C. H. Solomon, in an article entitled "Some Effects of Hydraulic Dredging and Coastal Development in Boca Ciega Bay, Florida", published in Fish Bulletin, 1968, Volume 67, Page 213, outlines the adverse effects of such loss of marine vegetation.
M. F. Godcharles in a Florida Department of Natural Resources Divison of Maritime Research Technical Services paper published 1971, Volume 64-1, brought these problems to light in the paper being entitled "A Study of the Effects of a Commercial Hydraulic Clam Dredge on Benthic Communities in Estuarine Areas".
A further reference work on the dangers to seagrasses brought about by pollution is entitled "Tropical Seagrass Ecosystems and Pollution in Tropic Marine Pollution". This discussion by J. D. Ziemen appears in the Wood & Johannes edition of Elsevier Oceanographer, Series 12-64, published 1975.
Research is under way into methods of restoring such endangered seagrasses particularly in view of the effect such seagrasses have on the cycling of nutrients, sediment stabilization and providing the necessary nursery and shelter habitats for a diversity of both plant and animal species.
The benefits derived from such restorative efforts is emphasized by C. P. McRoy and C. Helfferich in Applied Aspects of Seagrasses, a handbook of seagrass biology and by R. C. Phillips and C. P. McRoy, An Ecosystem Perspective, Garland STPM Press, Inc., New York, 1980, page 297.
In addition to the above, C. G. J. Patterson and P. Boysen-Jensen relate the value of such restoration of seagrasses in "Valuation of the Sea in Animal Life of the Sea Bottom, Its Food and Quantity", reproduced from Danish Biology, Volume 20-1, published 1911.
Referring more particularly to an area of cultivation that has been acclaimed by public and scientific committees, seagrasses that have received a certain amount of attention are Thalassia testudinum and Halodule wrightii, hereinunder referred to as Thalassia and Halodule, respectively.
A report of a Steering Committee of Seagrass Ecosystems Study was published in 1973 drawing attention to various problems associated with successful cultivation of seagrasses. Most of these studies as reported were relative to the laboratory cultivation of such seagrasses as Thalassia and it is to be noted that only marginal success was attained in these cultivation attempts.
Several prior proposals have been put forward for transplanting seagrasses from an indigenous meadow otherwise called a donor site. During one such study entitled "Restoration of Seagrasses with Economic Analysis" by A. Thorhaug and Austin published in Environmental Conservation, volume 3-259, published 1976, the Thalassia seeds were recovered and later used to develop by nursery-type procedures, the holding and developing of transplant stock for later use in the field.
Utilizing such transplant techniques, efforts have been made particularly in the Biscayne Bay area of Florida to use such transplant stock, Thalassia and Halodule. These transplants have been made by virtue of anchors of iron attached to such plants. Although such transplantation met with initial failure, recent experiments have met with much success. Nevertheless, the cost of such procedures has proven prohibitive.
For example, the cost of transplanting plugs of eelgrass in North Carolina averaged $76,545 per acre. In Long Island Sound, eelgrass sprigs were planted at less than 1 meter depth at a cost of $12,775 per acre.
In Florida, Thalassia seedlings were planted at variable costs depending on the time required to obtain the desired cover. To obtain a coverage of 2,000 blades per square meter within 0.8 years, the cost was as high as $56,487 per acre.
Because of these high costs and the resultant damage experienced by the donor site during removal of plants to be transplanted, such cultivation procedures have left much to be desired.
The present invention seeks to overcome the aforementioned inadequacies of the prior art by the provision of a system whereby plant life such as seagrass seeds can be grown using peat pellet techniques. The seeds are cultivated in pots containing these peat pellets, the pots being located within trays supported by a submersible raft anchored at the cultivation site.
U.S. Pat. No. 2,283,472 to Tuxhorn, discloses an apparatus for establishing fish habitats. This specification describes a float that rises and falls with the level of water in a lake. A submergible floating raft like structure is disclosed for supporting soil, rocks and materials necessary for growth of aquatic plants. However, this raft is not reusable.
Although the aforementioned patent solves many of the needs of the prior art for the cultivation of aquatic plants, this structure is relatively complex in construction and costly to manufacture. Therefore, it is a primary object of this invention to provide a submersible raft that overcomes the inadequacies of the prior art structure and provides an improvement which significantly contributes to the low cost of manufacture of a submersible raft.
Another object of the present invention is to provide a simple submersible raft that can easily be manufactured from standard polyvinyl chloride tubing and fittings.
Another object of the invention is to provide a submersible raft which supports a plurality of pots for the propagation of aquatic plants from seeds.
Another object of the present invention is the provision of a submersible raft which is reusable.
Another object of the invention is the provision of means for locking seed pot carrying trays relative to the submersible raft.
Another objective of the present invention is the provision of a sheet of netting which encompasses the submersible raft so that the formation of algae on the seed pots is inhibited.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the invention. Particularly with regard to the use of the invention disclosed herein, this should not be construed as limited to submersible rafts for the cultivation of aquatic plants, but should include rafts for the propagation of other forms of life within the aquatic environment.